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On a Miraphone 184 , is the main tuning slide the same size as the valve bore or is it larger? An easy way to check would be to pull out the main slide and the first and see if one side of the main fits in the first or vice versa.

If the main tuning slide is bigger, what's the bore size on each side of the slide? Are both sides of the main tuning slide the same size?

I'm mainly interested in CCs, but it would certainly be interesting if the BBb 184 was different or the same in this regard.

I have a 184CC in the shop and will check for you in the morning (if I can remember!)

It's for sale. Wanna buy it?

bloke wrote:The elbows past the fourth rotor on all of the 18X series Instruments feature expanding bores.

My 1965 American market BBb 186 has a symmetrical main tuning slide. I already knew that the 4th valve slide was not original because it's extra long, so maybe the main tuning slide and tubing around it are not original. But I'm pretty sure that the tech who recently made an alternative longer tuning slide said that he ordered the elbow from Miraphone, and it's also symmetrical.

Main tuning slide has a larger bore (symmetrical) in comparison to the valve section. BBb and CC 184 are the same.

Can anyone measure the bore of a 184 main tuning slide? I understand that both sides are the same. I'm curious about how much bigger they are then the valves.

bloke wrote:

anotherjtm2 wrote:

bloke wrote:The elbows past the fourth rotor on all of the 18X series Instruments feature expanding bores.

My 1965 American market BBb 186 has a symmetrical main tuning slide....

just to be clear:
Your statement and mine do not conflict with each other, and mine answers the original question.

Very true. Sorry about that. I must not have been thinking clearly, and should have known better.

bloke wrote:

anotherjtm2 wrote:additional information

It's all very good, sir.

Whew! I do have one tuba for which the first elbow after the valves is the main tuning slide, so that elbow changes gauge and the slide only fits one way.

So all but one of my questions have been answered.

So what's the bore size on each side of a 184 main tuning slide?

Valve bore size is 0,708 and main tuning slide bore is 0,740 inch.

Christian wrote:Valve bore size is 0,708 and main tuning slide bore is 0,740 inch.

Thanks Christian!

All the best,
Christian